Alloy



umTEosrAT s PATENT OFFICE...

znr :rnrrams AND WIL IZIAM A. emson, or GLEVELAND, omo, assrqnons 'ro rim ALUMINUM casmmes ,oomranv, or cnnvnmnnomo, aconronarron or 01110.

ALLOEL N0 Drawing.

To all whom it may concern:

Be it known that-we, ZAY Jnrrnms and- WILLIAM A. GIBSON, citizens of the United ticularly with aluminum alloys containing zinc as one of their constituents.

.One object of the invention is to provide an aluminum-zinc alloy having high tensile strength and elastic limit and also a sufliciently great ductility to render the alloy subjected to suitable. for uses where it is serve strains and shocks;

Another object of the invention is to pro vide an aluminum-zinc alloy which is susceptible to beneficial heat treatment.

Another object of the invention is to provide an aluminum-zinc alloy having su-v perior physical properties in combination with ease of preparation and good casting, machining-and working qualities.

In a "co-pending ap lication Serial No. 314,261, filed have described an aluminum alloy containlngzinc, copper and iron and have pointed for patent out the marked advantages possessed by it Since the development of that alloy we have discovered that the physical properties of an alloy of that character can be improved notably by the addition to the alloy of magnesium in suitable-small amounts, and it is this alloy containing magnesium that constitutes the subject matter of the present application. v

The advantages of our present invention, in the case of castings, can be secured in substantial measure by keeping the composition of the alloy within the following limits, although the proportions of the various constituents mayvaryfthrough. a con-,

' siderable range as shown in the co-pending fapplication, are by weight,

application and still retain to a certain de-; gree the'advantages'of thisalloy July 30th, 1919, we

Specification of Letters Patent.

Patented Sept. 7,1920.

Application filed m 30, 1919. Serial No. 314,262.

Alloys such as these, but without the magv nesium, as we have indicated in our co-pend-- 30,000 pounds per squareinch, elastic limits ranging from 15,000 pounds to 17,000 pounds %er square inch, elongations of about 6%,

rinell hardness numbers ranging between and and specific gravities less than 3.-

The marked effects from the addition of magnesium may bev indicated by a specific example representing a preferred composition. An'alloy composed of 8% zinc, 3% copper, 1% iron, l0.25% magnesium and the remainder aluminum, cast in green sand as V 7 before, we have found to show a 110118118 strength of over 35,000 pounds per square mch, elastic limit as? high as 30,000

: about 1.6%. Thus, the effect of adding the pounds per square inch and elongation of magnesium is markedly benefi'cial except in the case of the elongation, and we have found it-possible to overcome this difliculty by heat treatment, which results in some increase of the tensile strength and the elastic limit and in the very great increase of the elongation from about 1.6% to about 3.25%. We have found that about 0.25%

I magnesium, in the ease of castings, gives the maximum elongation.

Our improved alloys can be prepared in Various ways which will be obvious to those skilled in the .art but in practice we prefer to proceed as follows in preparing and using the alloys.

Copper and iron in the relative proportions required for the alloy are meltedtogether with sufficient aluminum to reduce the melting point of the mixture to approximately the melting point of aluminum.

To this alloy .is then added calculated amounts of. aluminum, zinc and magnesium.

The metalqshou'ld be thoroughly stirred during the melting and prior to the drawing off of the metal for ca tin so as 30,: a p

. 1 insure-a uniform mlxture. A pouring temperature of about 1300 in the ladle is suitable forthis alloy. The alloy can be cast either in sand molds or in'permanent".-. molds with'goodresults. In the cast condi-. tion it machines well and can also be rolled and otherwise worked.- Inathis' connection v it'isQto be noted that whe'n'fthe alloy'is to The percentag s here, aselsewherein be rolled or otherwise worked, a larger can be used without making the metal unduly hard and brittle, since such mechanical working "increases the ductility ofthe metal.

In the heat treatment of castings or articles made of the improved alloys we prefer to use the method of heat treatment which has been developed. by one-of us, namely,

v900 F. After the heating in this bath, the

castings or articles are removed and quenched in a bath of non-oxidizing 011 maintained at room temperature. After the quenching, the castings are reheated for about one hour in a bath of non-oxidizing oil maintained at a temperature of approximately 300 F. Following this heating in oil the articles are removed from the oil bath and permitted to cool in the air.

The effects of this heat treatment have been noted above, the most notable eifect bemg the large increase in the elongation, thus adapting the alloys for various structural uses which demand materials capable of withstanding severe shocks and strains.

As is Well known to those experienced in the commercial working of aluminum, the

metal available in commercial quantities always contains impurities, especially iron and silicon. Iron thus present should be allowed for in making upt lfe alloys and care should be taken to keep the silicon down to a minimum.

It will also be understood that While in the. foregoing description we have set forth the preferred compositions of the alloys and the preferred methods of preparing and heat treating them, we do not intend to limit our invention in these respects except as defined in the appended claims.

What we claim is:

1. An alloy containing aluminum from 1%to 25% zinc, from 2% to 5% of copper,

from 5% to 1.5% iron and an appreciable amount of magnesium.

2. An alloy containing aluminum from 4% to 16% of zinc, from 2% to 5% of copper, from .5% to 1.5% of iron, from .10% to 50% of magnesium with aluminum comprising the remainder.

3. An alloy containing 6% to 8% of zinc, 2.5% to 3.5% of copper, 11.0% to 1.5% of iron, from an appreciable amount to 0.50% of magnesium and with the remainder of the alloy composed of aluminum.

4:. An alloy containing 8% of zinc, 3% of copper, 1.2% of'iron, 0.25% of magnesium and with the remainder composed of aluminum. I

In testimony whereof we hereunto affix 

